Recently, as semiconductor devices are required to have higher speed and higher integration, lower resistance and smaller capacitance of the multilayer interconnection of the semiconductor devices are increasingly important objects. So far, for the low resistance of the multilayer interconnection, copper (Cu) has been used as an interconnection material. For the smaller capacitance of the multilayer interconnection, as the inter-layer insulation films with interconnections buried in, low dielectric constant (low-K) insulation films whose relative dielectric constants are lower than those of silicon oxide film and silicon nitride film are used.
For the interconnection structure thus using Cu as the interconnection material and low dielectric constant insulation films as the inter-layer insulation films, it is very important to improve the reliability of the interconnections represented by the electro-migration resistance and stress migration resistance.